1. Field of the Invention
The invention relates to an amplifier comprising a first output transistor and a second output transistor having the same polarity and arranged in push-pull configuration, and an input transistor whose collector is coupled to the base of the first output transistor.
2. Description of the Related Art
Such an amplifier is particularly known from the document JP-A-58-195306. It may be realized in an integrated form by using only transistors of the NPN type so that this amplifier is capable of working at a relatively high frequency.
As an intermediate frequency amplifier for television signals, the known amplifier is not completely satisfactory for different reasons:
Due to its asymmetrical structure, this amplifier does not allow elimination of parasitic signals which may be superimposed on the input signal and are amplified along with the useful signal. This drawback can be remedied by a differential structure instead of an asymmetrical one. For this purpose, one may consider to complete the known amplifier by means of a second part which is symmetrical with the first part and by using the two inputs and the two outputs of this structure in a differential mode. However, this solution does not have a sufficient rate of common mode rejection.
It would also be desirable to have an amplifier whose linearity is improved.